Natural skin is composed of many elements, including dermal fibroblasts and keratinocytes, hair follicles, nerves and blood vessels. Extracellular matrix components of skin, which are responsible for the strength, elasticity and turgor of native, healthy skin, include collagens, elastin and glycosaminoglycans. Collagen molecules provide the bulk of the tensile properties of all connective tissues in the human body, including skin. Elastin is a very long-lived protein that nonetheless breaks down in the skin of older individuals. Elastin breakdown contributes to skin drooping and wrinkles. Hydration is retained in skin by the presence of glycosaminoglycans, which act as “sponges” to retain water and provide skin with its natural turgor. Without these critical extracellular matrix components, skin becomes thin, wrinkled, and weak.
Various forms of injectable products have been developed for skin and other soft tissue augmentation. These products fall into synthetic and “natural” categories, wherein natural materials are derived from animal or human tissues. Synthetic materials that have been used as tissue bulking agents include silicone, oils and waxes, but these materials suffer from healing complications and are very viscous and difficult to inject. Animal-derived materials that have been described include bovine collagen in injectable forms. However, bovine collagen induces occasional immune reactions in recipients, due to the fact that bovine collagens are not identical to human collagens and can serve as antigens for immune reactivity. Other animal-derived extracellular matrix materials include hyaluronic acid that is derived from rooster combs. This material is quite viscous and also has the drawback of being of non-human origin. Additionally, various preparations of elastin currently in use have the drawback of inducing calcification upon implantation.
The compositions and methods of the present invention address these problems and fulfill a long felt need in the art.